fix(kotlin): propagate exceptions properly on failed parsing

cloud-kotlin/cloud-kotlin-coroutines-annotations/src/main/kotlin/org/incendo/cloud/kotlin/coroutines/annotations/KotlinAnnotatedMethods.kt

@@ -252,11 +252,15 @@ private class KotlinMethodArgumentParser<C, T>(
 
     @Suppress("UNCHECKED_CAST")
     private fun <T> CompletableFuture<*>.mapResult(): CompletableFuture<ArgumentParseResult<T>> =
-        thenApply {
-            when (it) {
-                null -> ArgumentParseResult.failure(IllegalArgumentException("Result not found"))
-                is ArgumentParseResult<*> -> it as ArgumentParseResult<T>
-                else -> ArgumentParseResult.success((it as T)!!)
+        handle { result, exception ->
+            if (exception != null) {
+                ArgumentParseResult.failure(exception)
+            } else {
+                when (result) {
+                    null -> ArgumentParseResult.failure(IllegalArgumentException("Result not found"))
+                    is ArgumentParseResult<*> -> result as ArgumentParseResult<T>
+                    else -> ArgumentParseResult.success((result as T)!!)
+                }
             }
         }
 }

cloud-kotlin/cloud-kotlin-coroutines-annotations/src/test/kotlin/org/incendo/cloud/kotlin/coroutines/annotations/KotlinAnnotatedMethodsTest.kt

@@ -190,6 +190,33 @@ class KotlinAnnotatedMethodsTest {
         }
     }
 
+    @Test
+    fun `test suspending parser method with exception`(): Unit = runBlocking {
+        AnnotationParser(commandManager, TestCommandSender::class.java)
+            .installCoroutineSupport()
+            .parse(ParserMethods())
+
+        val commandContext = StandardCommandContextFactory(commandManager).create(
+            true,
+            TestCommandSender()
+        )
+
+        val parser = commandManager.parserRegistry().createParser(
+            TypeToken.get(ParserResult3::class.java),
+            ParserParameters.empty()
+        )
+
+        assert(parser.isPresent) {
+            "Suspending parser cannot be found!"
+        }
+
+        val result: ArgumentParseResult<*> = parser.get().parseFuture(commandContext, CommandInput.of("5")).await()
+
+        assert(result.failure().orElse(null) is IllegalStateException) {
+            "Suspending parser should fail with IllegalStateException!"
+        }
+    }
+
     public class TestCommandSender
 
     private class TestCommandManager : CommandManager<TestCommandSender>(
@@ -236,6 +263,8 @@ class KotlinAnnotatedMethodsTest {
 
     data class ParserResult2(val test: Int)
 
+    data class ParserResult3(val test: Int)
+
     class ParserMethods {
 
         @Parser
@@ -249,5 +278,11 @@ class KotlinAnnotatedMethodsTest {
             withContext(Dispatchers.Default) {
                 ArgumentParseResult.success(ParserResult2(input.lastRemainingToken().toInt()))
             }
+
+        @Parser
+        suspend fun exceptionParser(input: CommandInput): ParserResult3 =
+            withContext(Dispatchers.Default) {
+                throw IllegalStateException()
+            }
     }
 }